The CMI Up Lift companion pulley combines a double snatch block with an ascender-style cam-lock system to hold the rope under tension once you stop the pull. Makes winching easier if you have to relax the load for any reason. eg change position of the winch etc. The 75 mm diameter sheave increases mechanical efficiency and the colour coding of the swing plates makes rigging easier - red for load rope, black for re-direction. The cam can be locked open (like ascenders) or retracted for quick remote release by the attached cord. The cam comes with a Lifetime Guarantee. The CMI Up Lift is designed to accept 10-12.5 mm ropes. Use to rig 3:1, 4:1 and 5:1 mechanical advantage systems as needed. Anodized aluminum side plates, two 75 mm milled aluminum sheaves, bushed with a stainless steel spindle. Made in the USA.